VS编程清空textbox出现错误，输入字符串的格式不正确。
namespace WindowsFormsApplication2{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
Double F, Y, f, L, δ = 0, ΔL1, ΔL2, ΔL, Result ,a;
String Flag;
private void textBox2_TextChanged(object sender, EventArgs e)
{
F = Convert.ToDouble(textBox2.Text);
}
private void textBox3_TextChanged(object sender, EventArgs e)
{
f = Convert.ToDouble(textBox3.Text);
}
private void textBox4_TextChanged(object sender, EventArgs e)
{
L = Convert.ToDouble(textBox4.Text)*1000;
}
private void button1_Click(object sender, EventArgs e)
{
//string str = textBox1.Text;
ΔL1 = (F * δ * Math.Pow(L, 2)) / (Math.Pow(f, 2) + F * δ * L);
ΔL2 = (F * δ * Math.Pow(L, 2)) / (Math.Pow(f, 2) - F * δ * L);
ΔL = ΔL1 + ΔL2;
//a = F * δ * Math.Pow(L, 2);
//Result = F + δ;
MessageBox.Show(Convert.ToString(ΔL));
//MessageBox.Show(Convert.ToString(ΔL1));
//MessageBox.Show(Convert.ToString(ΔL2));
//MessageBox.Show(Convert.ToString(ΔL));
}
private void label1_Click(object sender, EventArgs e)
{
}
private void label2_Click(object sender, EventArgs e)
{
}
private void label3_Click(object sender, EventArgs e)
{
}
private void label4_Click(object sender, EventArgs e)
{
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void textBox3_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 0x20) e.KeyChar = (char)0; //禁止空格键
//if (textBox3.Text.Trim() != "")
if ((e.KeyChar == 0x2D) && (((TextBox)sender).Text.Length == 0)) return; //处理负数
if (e.KeyChar > 0x20)
{
try
{
double.Parse(((TextBox)sender).Text + e.KeyChar.ToString());
}
catch
{
e.KeyChar = (char)0; //处理非法字符
}
}
}
private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 0x20) e.KeyChar = (char)0; //禁止空格键
//if (textBox2.Text.Trim() != "")
if ((e.KeyChar == 0x2D) && (((TextBox)sender).Text.Length == 0)) return; //处理负数
if (e.KeyChar > 0x20)
{
try
{
double.Parse(((TextBox)sender).Text + e.KeyChar.ToString());
}
catch
{
e.KeyChar = (char)0; //处理非法字符
}
}
}
private void textBox4_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar == 0x20) e.KeyChar = (char)0; //禁止空格键
//if (textBox4.Text.Trim() != "")
if ((e.KeyChar == 0x2D) && (((TextBox)sender).Text.Length == 0)) return; //处理负数
if (e.KeyChar > 0x20)
{
try
{
double.Parse(((TextBox)sender).Text + e.KeyChar.ToString());
}
catch
{
e.KeyChar = (char)0; //处理非法字符
}
}
}
